Method for producing fluorine-containing copolymers and fluorine-containing copolymers

Abstract

The fluorine-containing copolymer production method and the fluorine-containing copolymer according to the present invention involve performing solution polymerization using monomers including ethylene and tetrafluoroethylene, in a polymerization medium containing at least one polymerization solvent A selected from the group consisting of compounds represented by formulae 1-4. The descriptions regarding formulae 1-4 are omitted.

Description

[Technical Field]

[0001] This disclosure relates to a method for producing a fluorine-containing copolymer and to a fluorine-containing copolymer. [Background technology]

[0002] In recent years, fluorinated polymers have been utilized in a variety of applications due to their excellent heat resistance, solvent resistance, and chemical resistance.

[0003] Known polymerization methods for producing fluorine-based polymers include solution polymerization, suspension polymerization, and emulsion polymerization.

[0004] For example, Chinese Patent Application Publication No. 110467695 describes a method for carrying out a polymerization reaction in a mixture of water and an organic solvent using emulsion polymerization, with ethylene and tetrafluoroethylene as raw materials. Also, Japanese Patent Publication No. Hei 8-59717 describes a method for producing a hydrogen-containing fluoropolymer by (co)polymerizing in an organic suspension medium at a temperature of -60°C to 30°C in the presence of a radical photoinitiator and ultraviolet-visible light. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, the manufacturing methods described in Chinese Patent Application Publication No. 110467695 and Japanese Patent Publication No. P8-59717 have slow polymerization rates, and a more efficient method for obtaining fluorine-containing copolymers is desired.

[0006] According to embodiments of the present invention, a method for producing a fluorine-containing copolymer with a faster polymerization rate compared to conventional methods is provided, as well as a fluorine-containing copolymer obtained by this method. [Means for solving the problem]

[0007] This disclosure includes the following aspects: <1> A method for producing a fluorine-containing copolymer, comprising performing solution polymerization using monomers containing ethylene and tetrafluoroethylene in a polymerization medium containing at least one polymerization solvent A selected from the group consisting of compounds represented by the following formulas 1 to 4. [ka] [ka] [ka] [ka] In equation 1, Y 1 This represents a nitrogen atom or an oxygen atom, Y 1 When is a nitrogen atom, p, m, n, and k are each independent integers such that p+m is 1 or greater and p+m+n+k=3. Y 1 When is an oxygen atom, p, m, n, and k are each independent integers such that p+m is 1 or greater and p+m+n+k=2. When p is 1 or greater, then n is 1 or greater. In equation 2, Y 2 represents a carbon atom, silicon atom, phosphorus atom, or sulfur atom. Y 2 When is a carbon atom or a silicon atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=4. Y 2 When is a phosphorus atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=3. Y 2 When is a sulfur atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=2. When s is 1 or greater, u is 1 or greater, X independently represents a chlorine atom or a bromine atom, In Formula 1 and Formula 2, Z 1 independently represents a group represented by any one of the following Formulas T1 to T14, In Formula 3, Y 3 represents a carbon atom or a silicon atom, R 1 ~R 4 independently represents a methyl group, a tert-butyl group, or a tert-butoxy group, In Formula 4, Z 2 is a group represented by the following Formula T14.

Chemical formula

[0008] This disclosure provides a method for producing a fluorine-containing copolymer with a faster polymerization rate compared to conventional methods, and a fluorine-containing copolymer obtained by this method. [Modes for carrying out the invention]

[0009] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, unless otherwise specified, the amount of each component refers to the total amount of multiple substances if there are multiple substances corresponding to each component.

[0010] [Method for producing fluorine-containing copolymers] The method for producing a fluorine-containing copolymer according to this disclosure is a method of solution polymerization using monomers containing ethylene and tetrafluoroethylene in a polymerization medium containing at least one polymerization solvent A selected from the group consisting of compounds represented by the following formulas 1 to 4.

[0011] [ka]

[0012] [ka]

[0013] [ka]

[0014] [ka]

[0015] In equation 1, Y 1 This represents a nitrogen atom or an oxygen atom, Y 1 When is a nitrogen atom, p, m, n, and k are each independent integers such that p+m is 1 or greater and p+m+n+k=3. Y 1 When is an oxygen atom, p, m, n, and k are each independent integers such that p+m is 1 or greater and p+m+n+k=2. When p is 1 or greater, then n is 1 or greater. In equation 2, Y 2 represents a carbon atom, silicon atom, phosphorus atom, or sulfur atom. Y 2 When is a carbon atom or a silicon atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=4. Y 2 When is a phosphorus atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=3. Y 2 When is a sulfur atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=2. When s is 1 or greater, u is 1 or greater, Each X independently represents either a chlorine atom or a bromine atom. In equations 1 and 2, Z 1 Each of these is an independent group represented by one of the following formulas T1 to T14: In formula 3, Y 3 represents a carbon atom or a silicon atom, R 1 ~R 4 Each of these independently represents a methyl group, a tert-butyl group, or a tert-butoxy group. In equation 4, Z 2 This is a group represented by the following formula T14.

[0016] [ka]

[0017] In formulas T1 to T14, A 1 Each of these independently represents a hydrogen atom, a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR, and A 2 Each of the following independently represents a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR; each of the following independently represents a methyl group or a tert-butyl group; and * represents a bonding site.

[0018] The method for producing fluorine-containing copolymers according to this disclosure allows polymerization to proceed at a faster rate compared to conventional methods, thereby obtaining fluorine-containing copolymers. The inventors speculate that the reason for this effect is as follows.

[0019] In the method for producing fluorine-containing copolymers described herein, polymerization is carried out in a polymerization medium containing at least one polymerization solvent A selected from the group consisting of compounds represented by formulas 1 to 4. All of the polymerization solvents A have low chain transfer properties. Therefore, it is presumed that polymerization of monomers including ethylene and tetrafluoroethylene proceeds smoothly.

[0020] The method for producing the fluorine-containing copolymer and the fluorine-containing copolymer described herein will be explained in detail below.

[0021] (polymerization medium) The polymerization medium includes at least one polymerization solvent A selected from the group consisting of compounds represented by formulas 1 to 4.

[0022] <Compound represented by Formula 1> [ka]

[0023] In equation 1, Y 1 This represents a nitrogen atom or an oxygen atom. Y 1 When is a nitrogen atom, p, m, n, and k are independent integers such that p+m is 1 or greater and p+m+n+k=3. Y 1 When is an oxygen atom, p, m, n, and k are independent integers such that p+m is 1 or greater and p+m+n+k=2. When p is 1 or greater, then n is 1 or greater. Z 1 Each of these is an independent group that can be represented by one of the formulas T1 to T14.

[0024] In formulas T1 to T14, A 1 Each of these independently represents a hydrogen atom, a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR, and A 2 Each of the following independently represents a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR; each of the following independently represents a methyl group or a tert-butyl group; and * represents a bonding site.

[0025] [ka]

[0026] In Equation 1, the following combinations of p, m, n, and k are possible. Y 1 When is a nitrogen atom, (p, m, n, k)=(0, 1, 0, 2), (0, 1, 1, 1), (0, 1, 2, 0), (1, 0, 1, 1), (1, 0, 2, 0), (0, 2, 0, 1), (0, 2, 1, 0), (1, 1, 1, 0), (2, 0, 1, 0), (0, 3, 0, 0), Y 1 When is an oxygen atom, (p, m, n, k)=(0, 1, 0, 1), (0, 1, 1, 0), (1, 0, 1, 0), (0, 2, 0, 0)

[0027] From the viewpoint of increasing the polymerization rate and increasing the molecular weight, in formula 1, Y 1 It is preferable that the atom is an oxygen atom. In particular, the combination of p, m, n, and k is preferably (p, m, n, k) is (0, 1, 0, 1), (0, 1, 1, 0), or (1, 0, 1, 0).

[0028] When n is 1 or greater, Z 1 Each of these groups is independently a group represented by any one of formulas T1 to T14, preferably a group represented by any one of formulas T1 to T7, and more preferably a group represented by any one of formulas T1 to T3.

[0029] In formulas T1 to T14, A 1 Each of these independently represents a hydrogen atom, a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR, and A 2 Each of these independently represents a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR, and each R independently represents a methyl group or a tert-butyl group. Among them, A 1 Each of these independently represents a methyl group, a tert-butyl group, -OR, or -NR2, and A 2 Each of these independently represents a methyl group, a tert-butyl group, -OR, or -NR2, and R preferably independently represents a methyl group or a tert-butyl group.

[0030] In the compound represented by formula 1, Z 1 Examples include the following compounds:

[0031] [ka]

[0032] The following are specific examples of compounds represented by Formula 1, but the compounds represented by Formula 1 are not limited to these.

[0033] [ka]

[0034] [ka]

[0035] <Compound represented by formula 2> [ka]

[0036] In equation 2, Y 2 represents a carbon atom, silicon atom, phosphorus atom, or sulfur atom. Y 2 When is a carbon atom or a silicon atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=4. Y 2 When is a phosphorus atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=3. Y 2 When is a sulfur atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=2. When s is 1 or greater, then u is 1 or greater. Each X independently represents either a chlorine atom or a bromine atom. Z 1 Each of these is an independent group that can be represented by one of the formulas T1 to T14.

[0037] In Equation 2, the following combinations of s, t, u, and v are possible. Y 2 When is a carbon atom or a silicon atom, (s, t, u, v)=(0, 1, 0, 3), (0, 1, 1, 2), (0, 1, 2, 1), (0, 1, 3, 0), (1, 0, 1, 2), (1, 0, 2, 1), (1, 0, 3, 0), (0, 2, 0, 2), (0, 2, 1, 1) , (0, 2, 2, 0), (1, 1, 1, 1), (1, 1, 2, 0), (2, 0, 1, 1), (2, 0, 2, 0), (0, 3, 0, 1), (0, 3, 1, 0), (1, 2, 1, 0), (2, 1, 1, 0), (3, 0, 1, 0) Y 2 When is a phosphorus atom, (s, t, u, v)=(0, 1, 0, 2), (0, 1, 1, 1), (0, 1, 2, 0), (1, 0, 1, 1), (1, 0, 2, 0), (0, 2, 0, 1), (0, 2, 1, 0), (1, 1, 1, 0), (2, 0, 1, 0), (0, 3, 0, 0) Y 2 When is a sulfur atom, (s, t, u, v)=(0, 1, 0, 1), (0, 1, 1, 0), (1, 0, 1, 0), (0, 2, 0, 0)

[0038] Among them, the combination of s, t, u, and v is Y 2 When is a carbon atom, it is preferable that (s, t, u, v) is (3, 0, 1, 0), and Y 2 When is a phosphorus atom, it is preferable that (s, t, u, v) is (0, 3, 0, 0).

[0039] From the viewpoint of increasing the polymerization rate and increasing the molecular weight, in formula 2, Y 2 It is preferably a carbon atom, a silicon atom, or a sulfur atom, more preferably a carbon atom or a silicon atom, and even more preferably a carbon atom.

[0040] From the viewpoint of increasing the polymerization rate, it is preferable that X in formula 2 is a chlorine atom.

[0041] When u is 1 or greater, from the viewpoint of increasing the polymerization rate, Z 1Each of these groups is independently a group represented by any one of formulas T1 to T14, preferably a group represented by any one of formulas T1 to T7, and more preferably a group represented by any one of formulas T1 to T3.

[0042] In formulas T1 to T14, A 1 Each of these independently represents a hydrogen atom, a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR, and A 2 Each of these independently represents a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR, and each R independently represents a methyl group or a tert-butyl group. Among them, A 1 Each of these independently represents a methyl group, a tert-butyl group, -OR, or -NR2, and A 2 Each of these independently represents a methyl group, a tert-butyl group, -OR, or -NR2, and R preferably independently represents a methyl group or a tert-butyl group.

[0043] In the compound represented by formula 2, Z 1 For example, Z in the compound represented by formula 1 1 Similar examples include the above.

[0044] The following are specific examples of compounds represented by Equation 2, but the compounds represented by Equation 2 are not limited to these.

[0045] [ka]

[0046] <Compound represented by formula 3> [ka]

[0047] In formula 3, Y 3 represents a carbon atom or a silicon atom. R 1 ~R 4Each independently represents a methyl group, a tert-butyl group, or a tert-butoxy group.

[0048] Hereinafter, specific examples of the compound represented by Formula 3 are given, but the compound represented by Formula 3 is not limited thereto.

[0049]

Chemical formula

[0050] From the viewpoint of increasing the polymerization rate and increasing the molecular weight, in Formula 3, Y 3 is preferably a carbon atom.

[0051] Also, from the viewpoint of increasing the polymerization rate and increasing the molecular weight, in Formula 3, R 1 ~R 4 is preferably a methyl group.

[0052] <Compound represented by Formula 4>

Chemical formula

[0053] In Formula 4, Z 2 is a group represented by the following Formula T14.

[0054]

Chemical formula

[0055] That is, the compound represented by Formula 4 is acetonitrile.

[0056] Furthermore, in polymerization solvent A, any compound that corresponds to both the compound represented by formula 1 and the compound represented by formula 2 is considered to be the compound represented by formula 1. In other words, the compound represented by formula 2 does not include the compound represented by formula 1. Also, in polymerization solvent A, any compound that corresponds to both the compound represented by formula 1 and the compound represented by formula 3 is considered to be the compound represented by formula 1. In other words, the compound represented by formula 3 does not include the compound represented by formula 1.

[0057] For example, methyl pivalate and tert-butyl pivalate are compounds represented by formula 1 and also compounds represented by formula 2, but are treated as compounds represented by formula 1. That is, methyl pivalate and tert-butyl pivalate are not included in the compounds represented by formula 2. Also, di-tert-butyl ether is a compound represented by formula 1 and also a compound represented by formula 3, but is treated as a compound represented by formula 1. That is, di-tert-butyl ether is not included in the compounds represented by formula 3.

[0058] <Other polymerization solvents> In the method for producing a fluorine-containing copolymer according to this disclosure, the polymerization medium may contain polymerization solvents other than polymerization solvent A. However, from the viewpoint of increasing the polymerization rate, it is preferable that the polymerization medium does not contain other polymerization solvents and consists only of polymerization solvent A.

[0059] Examples of other polymerization solvents include aromatic hydrocarbon solvents such as benzene, toluene, and xylene; sulfoxide solvents such as dimethyl sulfoxide (DMSO); ketone solvents such as acetone and 2-butanone (methyl ethyl ketone); ether solvents such as tetrahydrofuran (THF) and dioxane; ester solvents such as ethyl acetate; and halogen solvents such as hexafluoroisopropanol, chloroform, 1H-perfluorohexane, 1H,1H,1H,2H,2H-perfluorooctane, 1,3-bis(trifluoromethyl)benzene, 1,4-bis(trifluoromethyl)benzene, benzotrifluoride, chlorobenzene, and 1,2-dichlorobenzene.

[0060] (Monomers containing ethylene and tetrafluoroethylene) In the method for producing the fluorine-containing copolymer of the present disclosure, monomers containing ethylene and tetrafluoroethylene are polymerized. That is, the fluorine-containing copolymer obtained by the method for producing the fluorine-containing copolymer of the present disclosure contains structural units derived from ethylene (hereinafter also referred to as "E units") and structural units derived from tetrafluoroethylene (hereinafter also referred to as "TFE units").

[0061] The monomers used for the polymerization may contain other monomers in addition to ethylene and tetrafluoroethylene. That is, the fluorine-containing copolymer may contain other structural units in addition to E units and TFE units.

[0062] Examples of other monomers in addition to ethylene and tetrafluoroethylene include the following monomers (1) to (7). The other monomers may be one kind or two or more kinds.

[0063] Monomer (1): CH2=CX 11 (CF2) n Y 11 The compound represented by. However, X 11 and Y 11 are each independently a hydrogen atom or a fluorine atom, and n is an integer of 2 to 8. Monomer (2): Fluoroolefins having a hydrogen atom in an ethylenically unsaturated group, such as vinylidene fluoride, vinyl fluoride, trifluoroethylene, and hexafluoroisobutylene. Monomer (3): Fluoroolefins that do not have hydrogen atoms in the ethylenically unsaturated group, such as hexafluoropropylene (excluding TFE). Monomers (4): Perfluoro(alkyl vinyl ethers) such as perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), and perfluoro(butyl vinyl ether). Monomer (5): Perfluoro(vinyl alkenyl ether) having two ethylenically unsaturated bonds and capable of cyclization polymerization, such as CF2=CFOCF2CF=CF2 and CF2=CFO(CF2)2CF=CF2. Monomer (6): Fluorine-containing monomers having an aliphatic ring structure, such as perfluoro(2,2-dimethyl-1,3-dioxol), 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxol, and perfluoro(2-methylene-4-methyl-1,3-dioxolane). Monomer (7): A monomer that has a polar functional group and does not contain a fluorine atom (hereinafter also referred to as a polar functional group-containing monomer).

[0064] Examples of polar functional groups include hydroxyl groups, carboxyl groups, epoxy groups, and acid anhydride residues. Among these, acid anhydride residues are preferred as polar functional groups.

[0065] Examples of monomers containing polar functional groups include vinyl ethers having hydroxyl and epoxy groups, unsaturated carboxylic acids (e.g., maleic acid, itaconic acid, citraconic acid, and undecylenic acid), and unsaturated polycarboxylic acid anhydrides (e.g., maleic anhydride, itaconic anhydride, citraconic anhydride, and hymic anhydride).

[0066] Among the above monomers (1) to (7), monomer (1) is preferred because it has good reactivity with ethylene and tetrafluoroethylene. Examples of monomers (1) include CH2=CF(CF2)2F, CH2=CF(CF2)3F, CH2=CF(CF2)4F, CH2=CF(CF2)5F, CH2=CF(CF2)8F, CH2=CF(CF2)2H, CH2=CF(CF2)3H, CH2=CF(CF2)4H, CH2=CF(CF2)5H, CH2=CF(CF2)8H, CH2=CH(CF2)2F, CH2=CH(CF2)3F, CH2=CH(CF2)4F, CH2=CH(CF2)5F, CH2=CH(CF2)6F, CH2=CH(CF2)8F, CH2=CH(CF2)2H, CH2=CH(CF2)3H, CH2=CH(CF2)4H, CH2=CH(CF2)5H, and CH2=CH(CF2)8H. Among them, monomer (1) is CH2=CH(CF2) n F is preferred. The integer n in monomer (1) is 2 to 8, preferably 3 to 7, and more preferably 4 to 6.

[0067] In the monomer used for polymerization, the content of other monomers is preferably 0.001 mol% to 20 mol%, more preferably 0.1 mol% to 15 mol%, and even more preferably 0.2 mol% to 5 mol%, relative to the total amount of monomers. If the other monomer is monomer (7), the content is preferably 0.01 mol% to 5 mol%, more preferably 0.05 mol% to 3 mol%, and even more preferably 0.1 mol% to 1 mol%.

[0068] Furthermore, the molar ratio of ethylene to tetrafluoroethylene (ethylene / tetrafluoroethylene) is preferably 20 / 80 to 80 / 20, more preferably 70 / 30 to 30 / 70, and even more preferably 50 / 50 to 35 / 65.

[0069] (Polymerization initiator) In the method for producing a fluorine-containing copolymer according to the present disclosure, it is preferable to use a polymerization initiator to initiate the polymerization reaction.

[0070] The polymerization initiator is preferably a radical polymerization initiator. Examples of radical polymerization initiators include azo compounds such as azobisisobutyronitrile and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); peroxy dicarbonates such as diisopropyl peroxy dicarbonate; peroxyesters such as tert-butyl peroxypivalate, tert-butyl peroxyisobutyrate, and tert-butyl peroxyacetate; and non-fluorinated diacyl peroxides such as diisobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, and lauroyl peroxide; (Z(CF2) p Examples include fluorinated diacyl peroxides such as COO)2 (where Z is a hydrogen atom, a fluorine atom, or a chlorine atom, and p is an integer from 1 to 10); perfluoro-tert-butyl peroxides; and inorganic peroxides such as potassium persulfate, sodium persulfate, and ammonium persulfate.

[0071] (Chain transfer agent) The method for producing a fluorine-containing copolymer according to this disclosure may involve carrying out the polymerization reaction in the presence of a chain transfer agent. The presence of a chain transfer agent makes it easier to adjust the molecular weight of the fluorine-containing polymer produced.

[0072] Examples of chain transfer agents include alcohols such as methanol, ethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoropropanol, 1,1,1,3,3,3-hexafluoroisopropanol, and 2,2,3,3,3-pentafluoropropanol; hydrocarbons such as n-pentane, n-hexane, and cyclohexane; hydrofluorocarbons such as CF2H2; ketones such as acetone; mercaptans such as methyl mercaptan; esters such as methyl acetate and ethyl acetate; and ethers such as diethyl ether and methyl ethyl ether.

[0073] (Polymerization method) The polymerization in the method for producing fluorine-containing copolymers according to this disclosure is solution polymerization. Solution polymerization is a polymerization method in which polymerization is carried out with monomers dissolved in a polymerization medium. Solution polymerization is distinguished from emulsion polymerization and suspension polymerization, which are carried out with monomers dispersed in a polymerization medium.

[0074] In the method for producing a fluorine-containing copolymer according to this disclosure, for example, the polymerization reaction is carried out by continuously or intermittently adding monomers containing ethylene and tetrafluoroethylene to a polymerization medium.

[0075] (Polymerization conditions) In the method for producing a fluorine-containing copolymer according to the present disclosure, at any stage during polymerization, the amount of substance (mol) of polymerization solvent A is changed to M sol S is the total solubility (mol / mol) of ethylene and tetrafluoroethylene in polymerization solvent A, and M is the total amount of substance (mol) of ethylene and tetrafluoroethylene dissolved in the polymerization medium. mon In this case, 0.5 ≤ M sol ×S / M mon It is preferable that the value be ≤ 1.0.

[0076] In this disclosure, "during polymerization" means the period during which a fluorine-containing copolymer containing ethylene and tetrafluoroethylene is being formed.

[0077] If the polymerization medium consists only of polymerization solvent A and does not contain any polymerization medium other than polymerization solvent A, then M sol ×S / M mon The result is 1.0. If the polymerization medium contains polymerization solvents other than polymerization solvent A, then M sol ×S / M mon The result will be less than 1.0.

[0078] M sol ×S / M mon When the ratio is between 0.5 and 1.0, chain transfer by the polymerization medium is suppressed, and the polymerization rate improves. From the viewpoint of further improving the polymerization rate, M sol ×S / M monIt is more preferably 0.7 to 1.0, and even more preferably 0.85 to 1.0.

[0079] <Amount of substance M of polymerization solvent A> sol > M represents the amount of substance of polymerization solvent A. sol It is calculated using the following formula. M sol (mol) = Weight of polymerization solvent A (g) / Molecular weight of polymerization solvent A The weight of polymerization solvent A shall be the value obtained by measurement under atmospheric pressure.

[0080] <Total solubility S of ethylene and tetrafluoroethylene in polymerization solvent A> The total solubility S of ethylene and tetrafluoroethylene in polymerization solvent A is calculated by the following method. First, the vapor pressure P of polymerization solvent A. sol Measure P sol This is the pressure observed when the polymerization medium is placed in a stainless steel autoclave with a stirrer, freeze-degassed twice, and the internal temperature of the reactor is maintained at a predetermined temperature T. T represents the liquid phase temperature. The temperature of the gas phase is assumed to be equal to the liquid phase temperature. Place the weighed polymerization solvent A into a stainless steel autoclave equipped with a stirrer. Calculate the amount of substance M' (mol) of polymerization solvent A based on its weight (g). Next, the weighed mixed gas of ethylene and tetrafluoroethylene is placed in a stainless steel autoclave equipped with a stirrer. At this time, the mixing ratio (molar ratio) of ethylene and tetrafluoroethylene is set to ethylene:tetrafluoroethylene = x:y. Amount of mixed gas of ethylene and tetrafluoroethylene to be charged: M all The amount in moles (mol) is calculated using the following formula, with the weight W (g) of the weighed mixed gas. M all =W / (28x+100y) When a sufficient amount of time has passed and the pressure has become constant, that pressure is called the total pressure P. all Let's assume that. Partial pressure P of a mixed gas of ethylene and tetrafluoroethylene monIt is calculated using the following formula. P mon =P all -P sol The volume V of the gas phase in a stainless steel autoclave with a stirrer can be calculated using the following formula. V = Volume of stainless steel autoclave with stirrer - Volume of polymerization solvent A The amount of substance M of the mixed gas of ethylene and tetrafluoroethylene present in the gas phase of a stainless steel autoclave with a stirrer. g The amount in moles ((mol)) is calculated using the following formula. Note that R represents the gas constant. M g =P mon V / RT The amount of substance M' of the mixed gas of ethylene and tetrafluoroethylene dissolved in polymerization solvent A. mon The amount in moles (mol) is calculated using the following formula. M' mon =M all -M g The total solubility S of ethylene and tetrafluoroethylene in polymerization solvent A is calculated using the following formula. S=M' mon / M'

[0081] <Total amount of ethylene and tetrafluoroethylene dissolved in the polymerization medium M mon > Total amount of ethylene and tetrafluoroethylene dissolved in the polymerization medium M mon It is calculated using the following method. First, the vapor pressure P' of the polymerization medium. sol Measure P' sol This is the pressure obtained when the heavy polymerization medium is placed in a stainless steel autoclave with a stirrer, freeze-degassed twice, and the internal temperature of the reactor is maintained at a predetermined temperature T. T represents the liquid phase temperature. The temperature of the gas phase is assumed to be equal to the liquid phase temperature. Next, the weighed mixed gas of ethylene and tetrafluoroethylene is placed in a stainless steel autoclave equipped with a stirrer. At this time, the mixing ratio (molar ratio) of ethylene and tetrafluoroethylene is set to ethylene:tetrafluoroethylene = x:y. Amount of mixed gas of ethylene and tetrafluoroethylene to be charged M' all The amount in moles (mol) is calculated using the following formula, with the weight W' (g) of the weighed mixed gas. M' all =W' / (28x+100y) When a sufficient amount of time has passed and the pressure has become constant, that pressure is the total pressure P'. all Let's assume that. Partial pressure P' of a mixed gas of ethylene and tetrafluoroethylene mon It is calculated using the following formula. P' mon =P' all -P' sol The volume V' of the gas phase in a stainless steel autoclave with a stirrer can be calculated using the following formula. V' = Volume of stainless steel autoclave with stirrer - Volume of polymerization medium The amount of substance M' of the mixed gas of ethylene and tetrafluoroethylene present in the gas phase of a stainless steel autoclave with a stirrer. g The amount in moles ((mol)) is calculated using the following formula. Note that R represents the gas constant. M' g =P' mon ×V' / RT The amount of substance M of the mixed gas of ethylene and tetrafluoroethylene dissolved in the polymerization medium. mon The amount in moles (mol) is calculated using the following formula. M mon =M' all -M' g

[0082] In the method for producing fluorine-containing copolymers according to this disclosure, the polymerization temperature is preferably 0°C to 100°C, and more preferably 20°C to 90°C. The polymerization pressure is preferably 0.1 MPaG to 10 MPaG, and more preferably 0.5 MPaG to 3 MPaG. The polymerization time is preferably 1 hour to 30 hours, and more preferably 2 hours to 20 hours.

[0083] [Fluorine-containing polymer] The fluorine-containing copolymers of this disclosure include structural units derived from ethylene and tetrafluoroethylene.

[0084] The fluorine-containing copolymers of this disclosure include E units and TFE units, and may also include other structural units other than E units and TFE units.

[0085] Other structural units include those derived from monomers (1) to (7) listed above as examples of monomers other than ethylene and tetrafluoroethylene.

[0086] In the fluorine-containing copolymer of this disclosure, the proportion of structural units other than E units and TFE units is preferably 0.001 mol% to 20 mol%, more preferably 0.1 mol% to 15 mol%, and even more preferably 0.2 to 5 mol%, based on the total amount of the fluorine-containing copolymer. If the other monomer is monomer (7), it is preferably 0.01 mol% to 5 mol%, more preferably 0.05 mol% to 3 mol%, and even more preferably 0.1 mol% to 1 mol%.

[0087] Furthermore, the molar ratio of E units to TFE units (E units / TFE units) is preferably 20 / 80 to 80 / 20, more preferably 70 / 30 to 30 / 70, and even more preferably 50 / 50 to 35 / 65.

[0088] (terminal group) The fluorine-containing copolymer of this disclosure has a total amount of terminal groups derived from at least one polymerization solvent A selected from the group consisting of compounds represented by the following formulas 1 to 4, which is 0.1 μmol / g to 100 μmol / g relative to the total mass of the fluorine-containing copolymer.

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093] In equation 1, Y 1 This represents a nitrogen atom or an oxygen atom, Y 1 When is a nitrogen atom, p, m, n, and k are each independent integers such that p+m is 1 or greater and p+m+n+k=3. Y 1 When is an oxygen atom, p, m, n, and k are each independent integers such that p+m is 1 or greater and p+m+n+k=2. When p is 1 or greater, then n is 1 or greater. In equation 2, Y 2 represents a carbon atom, silicon atom, phosphorus atom, or sulfur atom. Y 2 When is a carbon atom or a silicon atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=4. Y 2 When is a phosphorus atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=3. Y 2 When is a sulfur atom, s, t, u, and v are each independent integers such that s+t is 1 or greater and s+t+u+v=2. When s is 1 or greater, u is 1 or greater, Each X independently represents either a chlorine atom or a bromine atom. In equations 1 and 2, Z 1 Each of these is an independent group represented by one of the following formulas T1 to T14: In formula 3, Y 3 represents a carbon atom or a silicon atom, R 1 ~R 4 Each of these independently represents a methyl group, a tert-butyl group, or a tert-butoxy group. In equation 4, Z 2 This is a group represented by the following formula T14.

[0094] [ka]

[0095] In formulas T1 to T14, A 1 Each of these independently represents a hydrogen atom, a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR, and A 2 Each of the following independently represents a chlorine atom, a methyl group, a tert-butyl group, -OR, -NR2, or -SR; each of the following independently represents a methyl group or a tert-butyl group; and * represents a bonding site.

[0096] In this disclosure, "end group" means an atom or group of atoms bonded to an end atom constituting the main chain. Note that hydrogen atoms and X in formula (2) are not included in the term end group.

[0097] The amount of end groups derived from polymerization solvent A relative to the total mass of the fluorine-containing copolymer is preferably 0.5 μmol / g to 20.0 μmol / g, and more preferably 1.0 μmol / g to 10.0 μmol / g.

[0098] The amount of end groups derived from polymerization solvent A relative to the total mass of the fluorine-containing copolymer is measured using the following method.

[0099] First, in each polymerization solvent, 1500 cm³ -1 We focus on the peak wavelength at a higher wavelength and calculate the molar extinction coefficient at the peak wavelength of interest. The following lists each polymerization solvent and the peak wavelength of interest. Dimethyl carbonate (DMC): 1700-1800 cm -1 Methyl pivalate (MePiv): 1700-1800 cm -1 tert-butyl alcohol (t-BuOH): 3300~3600 cm³ -1 Di-tert-butyl carbonate (Boc2O): 1700~1800cm -1 N,N-dimethylformamide (DMF): 1600~1800 cm -1 Trimethyl phosphate (TMP): 3300-3600 cm -1 Acetonitrile (CH3CN): 2000-2500 cm -1 Di-tert-butylketone: 1500~1800cm -1 2-Chloro-2,4,4-trimethyl-3-pentanone: 1500~1800cm -1 tert-butylmethylsulfoxide: 1000-1200 cm -1 tert-butylmethylsulfone: 1000~1400cm -1

[0100] Using the calculated molar extinction coefficient, the concentration of the polymerization solvent incorporated into the polymer is calculated using the Lambert-Beer law. Absorbance A=εcd Note that ε represents the molar extinction coefficient (mL / (mol·cm)), c represents the polymer concentration in the solution (mol / mL), and d represents the optical path length (cm). The polymer density is measured in accordance with ASTM-D792. The sample IR transmission volume is calculated using the following formula. Sample IR transmission volume = IR beam diameter × polymer thickness From the obtained polymer concentration (mol / mL), the amount of substance of the end groups is calculated using the polymer density and IR permeation volume. [Examples]

[0101] The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to the following examples unless it exceeds the spirit of the disclosure.

[0102] [Example 1] A stainless steel autoclave with a stirrer and an internal volume of 600 mL was placed in an ice bath and held for 10 minutes. Then, 360 mL (4.29 mol) of dimethyl carbonate (indicated as "DMC" in the table) was charged as the polymerization medium, and freeze-degassing was performed twice. The reactor was heated to 30°C while being stirred, and a mixed gas of ethylene and tetrafluoroethylene (ethylene:tetrafluoroethylene (molar ratio) = 50:50) was injected under pressure to bring the reactor pressure to 1.5 MPaG. Furthermore, 21.9 mg (0.126 mmol) of diisobutyryl peroxide (product name "Perloyl IB", manufactured by NOF Corporation, "IBPO" in the table) was injected under pressure as a polymerization initiator, and the mixture was stirred at 200 rpm (200 revolutions per minute) for 3 hours while maintaining the internal temperature at 30°C. This yielded a polymer solution containing a copolymer of ethylene and tetrafluoroethylene. After the reactor was allowed to cool at room temperature, unreacted ethylene and tetrafluoroethylene were discharged. The resulting polymer solution was added to methanol, and the precipitate was filtered off. The precipitate was dried in a vacuum oven at 40°C for 12 hours. 33.9 g of copolymer of ethylene and tetrafluoroethylene was obtained. Dimethyl carbonate corresponds to the compound represented by formula 1, where Y 1 is an oxygen atom, p is 1, m is 0, n is 1, k is 0, Z 1 is a group represented by T1, and in T1, A 1 is -OR, where R is a methyl group.

[0103] [Example 2] A copolymer of ethylene, tetrafluoroethylene, and perfluorobutylethylene was obtained using the same method as in Example 1, except that 2.64 g (10.7 mmol) of perfluorobutylethylene, the monomer, was added when the polymerization medium, dimethyl carbonate, was added.

[0104] [Example 3] A copolymer of ethylene, tetrafluoroethylene, and perfluorobutylethylene was obtained using the same method as in Example 2, except that the polymerization initiator was changed to 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (product name "V70", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., "AMVN" in the table) and the polymerization temperature was changed to 35°C.

[0105] [Example 4] A copolymer of ethylene, tetrafluoroethylene, and perfluorobutylethylene was obtained using the same method as in Example 2, except that the polymerization initiator was changed to tert-butylperoxypivalate (product name "Perbutyl PV", manufactured by NOF Corporation, "PBPV" in the table) and the polymerization temperature was changed to 66°C.

[0106] [Example 5] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to di-tert-butyl carbonate (indicated as "Boc2O" in the table), the polymerization initiator was changed to diisopropyl peroxydicarbonate (product name "Perloyl IPP", manufactured by NOF Corporation, indicated as "IPP" in the table), and the polymerization temperature was changed to 45°C. Furthermore, di-tert-butyl carbonate corresponds to the compound represented by formula 1, where Y 1 is an oxygen atom, p is 0, m is 1, n is 1, k is 0, Z 1 teeth T5 It is a group represented by A in T1. 1 is -OR, and R is a tert-butyl group.

[0107] [Example 6] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to methyl pivalate ("MePiv" in the table). Furthermore, methyl pivalate corresponds to the compound represented by formula 1, where Y 1 is an oxygen atom, p is 1, m is 0, n is 1, k is 0, Z1 is a group represented by T1, and in T1, A 1 is a tert-butyl group.

[0108] [Example 7] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to tert-butyl alcohol (abbreviated as "t-BuOH" in the table). Note that t-butanol corresponds to the compound represented by Formula 1. In Formula 1, Y 1 is an oxygen atom, p is 0, m is 1, n is 0, and k is 1 as follows.

[0109] [Example 8] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to N,N-dimethylformamide (abbreviated as "DMF" in the table). Note that N,N-dimethylformamide corresponds to the compound represented by Formula 1. In Formula 1, Y 1 is a nitrogen atom, p is 2, m is 0, n is 1, k is 0, and Z 1 is a group represented by T1, and in T1, A 1 is a hydrogen atom.

[0110] [Example 9] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 5, except that the polymerization medium was changed to tri-tert-butylphosphine (abbreviated as "TTBP" in the table) and the polymerization temperature was changed to 35 °C. Note that tri-tert-butylphosphine corresponds to the compound represented by Formula 2. In Formula 2, Y 2 is a phosphorus atom, s is 0, t is 3, u is 0, and v is 0.

[0111] [Example 10] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to trimethyl phosphate (abbreviated as "TMP" in the table). Note that trimethyl phosphate corresponds to the compound represented by Formula 1. In Formula 1, Y 1is an oxygen atom, p is 1, m is 0, n is 1, k is 0, and Z 1 is a group represented by T3, and in T3, A 2 is -OR, and R is a methyl group.

[0112] [Example 11] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to tetramethylsilane ("TMS" in the table) and the polymerization temperature was changed to 25°C. Note that tetramethylsilane corresponds to the compound represented by Formula 3. In Formula 3, Y 3 is a silicon atom, and R 1 ~R 4 are methyl groups.

[0113] [Example 12] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to a mixture of dimethyl carbonate and methyl ethyl ketone ("MEK" in the table) (molar ratio 85:15) ("DMC / MEK = 85 / 15" in the table).

[0114] [Example 13] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to a mixture of dimethyl carbonate and methyl ethyl ketone ("MEK" in the table) (molar ratio 70:30) ("DMC / MEK = 70 / 30" in the table).

[0115] [Example 14] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to a mixture of acetonitrile ("CH3CN" in the table) and dimethyl carbonate (molar ratio 50:50) ("CH3CN / DMC = 50 / 50" in the table). Note that acetonitrile corresponds to the compound represented by Formula 4. In Formula 4, Z 2 is a group represented by T14.

[0116] [Example 15] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to neopentane and the polymerization temperature was changed to 20°C. Furthermore, neopentane corresponds to the compound represented by formula 3, and in formula 3, Y 3 R is a carbon atom, 1 ~R 4 It is a methyl group.

[0117] [Example 16] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to distilled and purified di-tert-butyl ketone. Furthermore, di-tert-butylketone corresponds to the compound represented by formula 2, where Y 2 is a carbon atom, s is 3, t is 0, u is 1, v is 0, Z 1 is a group represented by T1, and in T1, A 1 It is a tert-butyl group.

[0118] [Example 17] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to 2-chloro-2,4,4-trimethyl-3-pentanone. Furthermore, 2-chloro-2,4,4-trimethyl-3-pentanone corresponds to the compound represented by formula 2, where Y 2 is a carbon atom, s is 2, t is 0, u is 1, v is 1, X is a chlorine atom, Z 1 is a group represented by T1, and in T1, A 1 It is a tert-butyl group.

[0119] [Example 18] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to tert-butyl methyl sulfoxide. Furthermore, tert-butylmethyl sulfoxide corresponds to the compound represented by formula 2, where Y 2 is a carbon atom, s is 3, t is 0, u is 1, v is 0, Z 1is a group represented by T7, and in T7, A 2 It is a methyl group.

[0120] [Example 19] A copolymer of ethylene and tetrafluoroethylene was obtained in the same manner as in Example 1, except that the polymerization medium was changed to tert-butylmethylsulfone. Furthermore, tert-butylmethylsulfone corresponds to the compound represented by formula 2, where Y 2 is a carbon atom, s is 3, t is 0, u is 1, v is 0, Z 1 is a group represented by T9, and in T9, A 2 It is a methyl group.

[0121] [Example 20] An attempt was made to obtain a copolymer of ethylene and tetrafluoroethylene using the same method as in Example 1, except that the polymerization medium was changed to acetone. However, the copolymer was not obtained. Acetone does not correspond to polymerization solvent A.

[0122] [Example 21] An attempt was made to obtain a copolymer of ethylene and tetrafluoroethylene using the same method as in Example 1, except that the polymerization medium was changed to tert-butyl methyl ether (indicated as "TBME" in the table). However, no copolymer was obtained. Tert-butyl methyl ether does not correspond to polymerization solvent A.

[0123] [Example 22] An attempt was made to obtain a copolymer of ethylene and tetrafluoroethylene using the same method as in Example 1, except that the polymerization medium was changed to trimethyl phosphite (indicated as "P(OMe)3" in the table). However, no copolymer was obtained. Trimethyl phosphite does not correspond to polymerization solvent A.

[0124] The polymerization rate in the manufacturing methods of Examples 1 to 19, the melt flow rate (MFR) of the copolymers obtained in Examples 1 to 19, and the amount of end groups derived from polymerization solvent A were measured. In addition, the amount of substance (mol) of polymerization solvent A during polymerization was measured. solLet S be the total solubility (mol / mol) of ethylene and tetrafluoroethylene in the overlapping solvent A, and M be the total amount of substance (mol) of ethylene and tetrafluoroethylene dissolved in the polymerization medium. mon When M sol ×S / M mon was calculated. The measurement method and calculation method are as follows. For those that could not be measured, “-” was used in the table.

[0125] <Polymerization rate> The polymerization rate was calculated from the following formula. Polymerization rate (g / h·L) = yield of the obtained copolymer (g) / {polymerization time (h) · volume of the polymerization solvent (L)} Here, the polymerization solvent does not include the polymerization initiator.

[0126] <MFR value> Using a thermal flow evaluation apparatus (product name “Flow Tester CFT - 100EX”, manufactured by Shimadzu Corporation), in accordance with ASTM D3159, under the conditions of temperature: 297°C, load: 49.0 N, the mass (g) of the copolymer flowing out from an orifice with a diameter of 2.095 mm and a length of 8.000 mm in 10 minutes was measured and taken as MFR (g / 10 min).

[0127] <Amount of substance of terminal groups derived from polymerization solvent A> First, in each polymerization solvent, focusing on the peak wavelength on the higher wavelength side than 1500 cm -1 the molar absorption coefficient at the focused peak wavelength was calculated. The following shows each polymerization solvent and the focused peak wavelength. Dimethyl carbonate (DMC): 1700 - 1800 cm -1 Methyl pivalate (MePiv): 1700 - 1800 cm -1 tert - Butyl alcohol (t - BuOH): 3300 - 3600 cm -1 Di - tert - butyl carbonate (Boc2O): 1700 - 1800 cm -1 N,N-dimethylformamide (DMF): 1600~1800 cm -1 Trimethyl phosphate (TMP): 3300-3600 cm -1 Acetonitrile (CH3CN): 2000-2500 cm -1 Di-tert-butylketone: 1500~1800cm -1 2-Chloro-2,4,4-trimethyl-3-pentanone: 1500~1800cm -1 tert-butylmethylsulfoxide: 1000-1200 cm -1 tert-butylmethylsulfone: 1000~1400cm -1

[0128] Using the calculated molar extinction coefficient, the concentration of the polymerization solvent incorporated into the polymer was calculated using the Lambert-Beer law. Absorbance A=εcd Note that ε represents the molar extinction coefficient (mL / (mol·cm)), c represents the polymer concentration in the solution (mol / mL), and d represents the optical path length (cm). The polymer density was measured in accordance with ASTM-D792. The sample IR transmission volume was also calculated using the following formula. Sample IR transmission volume = IR beam diameter × polymer thickness From the obtained polymer concentration (mol / mL), the amount of substance of the end groups was calculated using the polymer density and IR permeation volume.

[0129] <M sol ×S / M mon > First, as mentioned above, M is the amount of substance (mol) of polymerization solvent A. sol The total solubility of ethylene and tetrafluoroethylene in polymerization solvent A (mol / mol) S, and the total amount of substance of ethylene and tetrafluoroethylene dissolved in the polymerization medium (mol) M. mon We calculated M sol , S, and M monUsing M sol ×S / M mon The result was calculated.

[0130] Table 1 lists the types of monomers, polymerization media, and polymerization initiators, the amount of end groups derived from polymerization solvent A, and the polymerization rate and MFR. When ethylene and tetrafluoroethylene are used as monomers, it is described as a binary system, and when ethylene, tetrafluoroethylene, and perfluorobutylethylene are used, it is described as a ternary system.

[0131] [Table 1]

[0132] As shown in Table 1, in Examples 1 to 19, solution polymerization was performed using monomers including ethylene and tetrafluoroethylene in a polymerization medium containing at least one polymerization solvent A selected from the group consisting of compounds represented by formulas 1 to 4, resulting in a faster polymerization rate than conventional methods.

[0133] Furthermore, the disclosure of Japanese Patent Application No. 2021-002103, filed on January 8, 2021, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. Solution polymerization is carried out in a polymerization medium containing at least one polymerization solvent A selected from the group consisting of compounds represented by the following formulas 1 to 4, using monomers containing ethylene and tetrafluoroethylene and a polymerization initiator. In the monomer containing ethylene and tetrafluoroethylene, the molar ratio of ethylene to tetrafluoroethylene (ethylene / tetrafluoroethylene) is 20 / 80 to 80 / 20. A method for producing a fluorine-containing copolymer, wherein the content of monomers other than ethylene and tetrafluoroethylene is 0.001 mol% to 20 mol% relative to the total amount of monomers. 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 In formula 1, Y １ This represents a nitrogen atom or an oxygen atom, Y １ When is a nitrogen atom, p, m, n, and k are each independent integers such that p+m is 1 or greater and p+m+n+k=3. Y １ When is an oxygen atom, the combinations of p, m, n, and k are (p, m, n, k) (1, 0, 1, 0) or (0, 1, 1, 0), When p is 1 or greater, n is 1 or greater, In formula 2, Y ２ represents a carbon atom, silicon atom, phosphorus atom, or sulfur atom. Y ２ When is a carbon atom or a silicon atom, s, t, u, and v are each independent integers such that s + t is 1 or greater and s + t + u + v = 4. Y ２ When is a phosphorus atom, s, t, u, and v are each independent integers such that s + t is 1 or greater and s + t + u + v = 3. Y ２ When is a sulfur atom, s, t, u, and v are each independent integers such that s + t is 1 or greater and s + t + u + v = 2. When s is 1 or greater, u is 1 or greater, Each X independently represents either a chlorine atom or a bromine atom. In equations 1 and 2, Z １ Each of these is an independent group represented by one of the following formulas T1 to T14, In Formula 3, Y ３ represents a silicon atom, R １ ~R ４ Each of these independently represents a methyl group. In formula 4, Z ２ This is a group represented by the following formula T14. 【Transformation 5】 In formulas T1 to T14, A １ Each of these independently consists of a hydrogen atom, a chlorine atom, a methyl group, a tert-butyl group, -OR, and -NR. ２ , or -SR represents A ２ These are, independently, a chlorine atom, a methyl group, a tert-butyl group, -OR, and -NR. ２ , or -SR represents, where R independently represents a methyl group or a tert-butyl group, and * represents a bonding site.

2. In the above equation 2, Y ２ A method for producing a fluorine-containing copolymer according to claim 1, wherein represents a carbon atom, a silicon atom, or a sulfur atom.

3. In the above equation 2, Y ２ A method for producing a fluorine-containing copolymer according to claim 1, wherein represents a carbon atom or a silicon atom.

4. A method for producing a fluorine-containing copolymer according to any one of claims 1 to 3, wherein X represents a chlorine atom in formula 2.

5. In the above formulas T1 to T14, A １ Each of these is independently a methyl group, a tert-butyl group, -OR, or -NR ２ This represents A ２ Each of these is independently a methyl group, a tert-butyl group, -OR, or -NR ２ A method for producing a fluorine-containing copolymer according to any one of claims 1 to 4, wherein R represents a methyl group or a tert-butyl group independently.

6. In formulas 1 and 2, Z １ A method for producing a fluorine-containing copolymer according to any one of claims 1 to 5, wherein each of the groups is independently represented by one of the formulas T1 to T7.

7. In formulas 1 and 2, Z １ A method for producing a fluorine-containing copolymer according to any one of claims 1 to 6, wherein each of the groups is independently represented by one of the formulas T1 to T3.

8. At any stage during polymerization, the amount of substance (mol) of the polymerization solvent A is set to M ｓｏｌ S is the total solubility (mol / mol) of ethylene and tetrafluoroethylene in the polymerization solvent A, and M is the total amount of substance (mol) of ethylene and tetrafluoroethylene dissolved in the polymerization medium. ｍｏｎ In that case, 0.5 ≤ M ｓｏｌ ×S / M ｍｏｎ A method for producing a fluorine-containing copolymer according to any one of claims 1 to 7, satisfying ≤ 1.

0.

9. It contains structural units derived from ethylene and tetrafluoroethylene, The amount of end groups derived from at least one polymerization solvent A selected from the group consisting of compounds represented by the following formulas 1 to 4 is 0.1 μmol / g to 100 μmol / g relative to the total mass of the fluorine-containing copolymer. In the fluorine-containing copolymer, the molar ratio of E units to TFE units (E units / TFE units) is 20 / 80 to 80 / 20. In the fluorine-containing copolymer, the proportion of structural units other than the E unit and TFE unit is 0.001 mol% to 20 mol% of the total amount of the fluorine-containing copolymer. 【Transformation 6】 【Transformation 7】 【Transformation 8】 【Chemistry 9】 In formula 1, Y １ This represents a nitrogen atom or an oxygen atom, Y １ When is a nitrogen atom, p, m, n, and k are each independent integers such that p+m is 1 or greater and p+m+n+k=3. Y １ When is an oxygen atom, the combinations of p, m, n, and k are (p, m, n, k) (1, 0, 1, 0) or (0, 1, 1, 0), When p is 1 or greater, n is 1 or greater, In formula 2, Y ２ represents a carbon atom, silicon atom, phosphorus atom, or sulfur atom. Y ２ When is a carbon atom or a silicon atom, s, t, u, and v are each independent integers such that s + t is 1 or greater and s + t + u + v = 4. Y ２ When is a phosphorus atom, s, t, u, and v are each independent integers such that s + t is 1 or greater and s + t + u + v = 3. Y ２ When is a sulfur atom, s, t, u, and v are each independent integers such that s + t is 1 or greater and s + t + u + v = 2. When s is 1 or greater, u is 1 or greater, Each X independently represents either a chlorine atom or a bromine atom. In equations 1 and 2, Z １ Each of these is an independent group represented by one of the following formulas T1 to T14, In formula 3, Y ３ This represents a silicon atom, R １ ~R ４ Each of these independently represents a methyl group. In formula 4, Z ２ This is a group represented by the following formula T14. 【Chemistry 10】 In formulas T1 to T14, A １ Each of these independently consists of a hydrogen atom, a chlorine atom, a methyl group, a tert-butyl group, -OR, and -NR. ２ , or -SR represents A ２ These are, independently, a chlorine atom, a methyl group, a tert-butyl group, -OR, and -NR. ２ , or -SR represents, where R independently represents a methyl group or a tert-butyl group, and * represents a bonding site.

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